The detrimental effects of soil pesticides :au. soil micro biota and biodiversity of the tea ecosystem are poorly understood. In the current study, microbial activity in southern tea soils of Sri Lanka as affected by application of commonly used soil pesticides and certain cultural practices was evaluated by measuring the soil respiration in vitro and in vivo.

Southern tea soils with low organic matter contents are exposed to repeated application of herbicides and negligence of important agronomic practices due to labor shortage. Such malpractices could aggravate potential build up of pesticide residues in the soil. Thus, improvement of soil organic matter status by incorporation of various organic amendments, establishment of green manure crops, rehabilitation of old tea soils and more importantly, restricted usage of agro-chemicals etc. is essential. These practices will assure long-term sustainable productivity and quality of soils as well as help degrade accumulated chemical residues and elevate densities of soil microbial communities. As a consequence, increased efficacy of bio control of nematodes and soil borne pathogens and proper administration of natural nutrient cycles could be envisaged.